Abstract. Whether antihydrogen qualifies as patentable subject matter for the purposes of the United States patent law is not an easy question. In general, man-made inventions and new compositions of matter are proper subjects of patent protection, while products of nature are not. Antihydrogen, a newly created element made entirely of antimatter, has qualities of both a newly created composition of matter and a product of nature. As a result, antihydrogen approaches the theoretical boundaries of the product of nature doctrine because mankind finally has the opportunity to create for the very first time an element that has probably never existed before in the entire universe.